When 20,000 people leave Hopkinton, Mass., for their marathon to Boston Monday morning, the running shoes they'll be wearing will be a far cry from the leather footgear the 110-year-old race's early participants wore.

These shoes will be lighter, tougher and tailored for every sort of runner, from the flat-footed plodder in the back of the pack to the elite Kenyans wearing 5-ounce "racing flats."

But in a few years, it's likely that the shoes worn in Monday's race will seem just as archaic as the old leathers. New shoes--some already in stores and some soon to hit--come with everything from computer chips to cutting-edge materials designed to better absorb foot pounding.

Some of these shoes have a steep price tag. A team of eight designers at Adidas-Salomon spent nearly three years working on a $250 shoe called the Adidas_1.

Adidas_1 has a chip embedded in its sole that senses how a foot is striking the ground. That chip communicates information to a motor, which is attached with a wire to a plate in the heel. If the motor increases tension on the wire, the heel stiffens. If it eases, the heel softens.

The idea is to create a "smart" shoe that alters itself for the gait and foot of a runner. The designers worked on it secretly, even baking their own circuit boards in a toaster oven so they wouldn't have to tell anyone what they were working on. And the original motors they experimented with were plucked from Furby children's dolls, said Michael Browne, Adidas' business unit manager for running in the United States. Adidas released the first version in 2004, and last fall shipped an update with a faster microprocessor.

"At Adidas, they're trying to make a shoe that adapts to the runner's foot," said Pete Humphrey, vice president of research and development at Brooks Sports. "Everyone is working on that. Whether it's computer chips or even nanotechnology, people are taking different paths to get there."

Brooks plans to release in July running shoes based on a material they call "Mogo." Humphrey won't say exactly what's in Mogo, which took them four years and 40 rounds of polymer combinations to create. But the idea was to create new material that absorbed more energy when hitting the ground while remaining more pliable than other materials. Mogo will be in Brooks' regular running shoes, and prices shouldn't be affected.

Nanotechnology is likely the next step in this technology competition.

We're looking at adaptive foams with intelligent molecules," Humphrey said. "I can't give you much more than that."